How fine is your grind?
M. Chase Scott, Extension Agent, Virginia Tech
It’s hard to open any recent dairy industry periodical and not see articles discussing high feed prices and low milk-to-feed ratios. Regardless of how high or low feed or milk prices are, dairy producers should always be looking for the biggest bang for their buck. If buying ground corn, either in a mix or alone, you should be aware of how finely the corn is ground.
Cracked corn or coarser ground corn has lower processing cost but is not as efficiently used by dairy cattle. Grinding corn finer increases the surface area available for digestion. By decreasing the grind size, you may be able to improve the energy utilization and increase milk production with the same amount of corn. Table 1 shows the difference in performance between cracked corn and ground corn. Cows receiving ground corn had a slightly higher DMI, they produced six more pounds of milk per day and tended to have a higher fat and protein percent.
So how do you know if your corn is ground fine enough? The most definitive method of determining grind size is sifting the corn through grain particle screens. Ground corn should be evaluated with the following sizes of screens: #4, #8, #16, #30 and a bottom pan. Table 2 lists the recommended distribution percentages of particle size for ground corn, both dry and high-moisture 25 to 30 percent. PD
—From Virginia Tech Dairy Pipeline, March 2007
Chase Scott
Dairy Extension Agent
What stage of lactation does corn particle size affect most? (dry, fresh, mid, late, or a combination)
Economically speaking the high price of energy dictates that corn is ground fine enough to maximize utilization. However, nutritionally speaking fresh or transition cows can be experiencing a high level of stress including but not limited to calving, group/facility changes and high milk production.
Cows that are in a negative energy balance, which is common among early lactation cows, require an energy dense ration that can support high levels of production; in this case the grind size of corn should be at a level that maximizes the amount of energy utilization during a period in which dry matter intake (DMI) struggles to “keep up” with production.
